Sulfur transportation in pipelines

ABSTRACT

An improved method of transporting sulfur-liquid hydrocarbon slurries through pipelines without causing sulfur agglomeration, sticking, deposition or plugging of the pipelines. The invention relates to an improved and novel process of preventing sulfur agglomeration, sticking, deposition and plugging of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry.

United States Patent Lewis Philip Reiss;

Frank L. Meyer, both of Houston, Tex. 784,924

Dec. 18, 1968 June 1, 1971 Shell Oil Company New York, N.Y.

Inventors Appl. No. Filed Patented Assignee SULFUR TRANSPORTATION IN PlPELlNES 6 Claims, No Drawings [56] References Cited UNITED STATES PATENTS 2,798,772 7/1957 Redcay 302/14 3,443,837 5/1969 Meyer et al. 302/14 Primary ExaminerAndres H. Nielsen Attorneys-George G. Pritzker and J. H. McCarthy ABSTRACT: An improved method of transporting sulfurliquid hydrocarbon slurries through pipelines without causing sulfur agglomeration, sticking, deposition or plugging of the pipelines.

The invention relates to an improved and novel process of preventing sulfur agglomeration, sticking, deposition and plugging of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry.

SULFUR TRANSPORTATION IN PIPELINES BACKGROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurry in pipelines is well known in the art as noted by reference to U.S. Pat. Nos. 2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry, June 1967, pages 58-60. In making the sulfur into a sulfur-hydrocarbon slurry, the sulfur is generally sprayed in molten form into either water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is es-.

sential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, agglomeration and separation ofthe sulfur from the carrier fluid, plating, depositing or coating of the sulfur on pipeline walls causing plugging of the pipeline, corrosion, viscosity changes due to pressure and temperature variations requiring greater pumping power which increases operation costs, etc., are only a few of the problems normally encountered in transporting sulfur-liquid hydrocarbon slurries through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be made to be an effective attractive and economic means of sulfur transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transportation of sulfur slurries such as injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry for pipeline transportation. These methods for making sulfur slurries suitable for transporting through pipelines generally do not overcome the agglomeration, deposition, sticking, coating and/or plugging problems described above.

An object of the present invention is transport sulfur as a sulfur-liquid hydrocarbon slurry through pipelines which is stable and flowable.

Still another object of the present invention is to transport through a pipeline sulfur-liquid hydrocarbon slurries without causing sulfur agglomeration, coating, deposition or plugging of the pipeline.

Still another object of this invention is to form a slurry of sulfur in a liquid hydrocarbon medium, which does not tend to cause sticking, agglomeration or pipeline plugging or cause any difficulty in circulation of the slurry when said slurry is pumped and transported through a pipeline and from which the sulfur can be readily recovered at the terminal end of the pipeline as essentially pure sulfur.

Another object is to transport sulfur as a liquid hydrocarbon slurry by pipeline over great distances under conditions of reduced pumping and handling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to an improved, novel and new technique for transporting a slurry of a sulfur-liquid petroleum fraction through pipelines over great distances without causing sulfur agglomeration or sticking or sulfur deposition on the walls of the pipelines due to the tendency of sulfur under such conditions to adhere to the pipeline walls because of temperature, pressure and other variable conditions so as to plug said lines; by admixing or adding or injecting prior to or after injection into the pipeline of a slurry of sulfur and a liquid petroleum fraction, which fraction can be a distillate or condensate petroleum fraction ranging in viscosity from a gasoline to a heavy lube oil fraction such as gasoline, kerosene, fuel oil, lubricating oil and fractions and mixtures thereof, a small amount of from 0.l percent to percent, preferably between about 0.5 percent to about 5 percent of a crude oil which can be refined or unrefined and preferably an unrefined crude oil. The crude oil can be added to the slurry or sulfur and liquid petroleum fraction as described prior to or during the making of the slurry or the crude oil can be injected when necessary in various places along the pipeline where indications are that the slurry might cause sulfur agglomeration, deposition, sticking or plugging of the line. Any plugging detection means known in the art can be used for this purpose. It has been noted that by adding or injecting into a slurry of the sulfur and liquid petroleum fraction, e.g., kerosene or oil condensate before, during or after the slurry preparation, from about 0.1 to 10 percent of crude oil in which the sulfur content of the slurry can vary from about 10 percent to about 75 percent by weight or higher, preferably between 30 and 70 percent by weight sulfur, that not only does the presence of the crude oil prevent plugging of pipelines transporting said slurry but also preventing agglomeration, sticking and deposition of sulfur on the walls of the pipelines and improves fiow of r the slurry and reduces pumping costs.

The sulfur-liquid petroleum fraction slurry can be made by. any suitable means such as described in U.S. Pat. No. 2,798,772 or by the method described in copending U.S. Pat. application Ser. No. 663,755, filed Aug. 28, 1967 which matured as U.S. Pat. No. 3,443,837. It is preferred that in the making the sulfur-liquid petroleum fraction slurry that the sulfur is produced in spherical form since sulfur in this form in the slurry is resistant to agglomeration attrition and friction.

The phase transfer method for making the sulfur slurry as described in the above-mentioned copending application comprises first forming a sulfur-aqueous liquid (water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon. The sulfur may be phase transferred directly into crude oil. Thereafter, the crude oil can be added as desired.

The liquid petroleum carrier for the sulfur can be one ranging in viscosity from a light petroleum fraction such as liquefied petroleum gas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleum distillates, condensates, and mixtures thereof. Preferred are liquid petroleum fractions containing at least l0 percent or higher of aromatics, preferably about 15- -30 percent aromatic enriched kerosene or oil condensate fractions containing l520 percent aromatics which include monoand polyaromatic hydrocarbons. The carrier may be percent crude oil.

The crude oil additive should be unrefined crude oil. By unrefined crude oil is meant any crude oil which has not been processed in a refinery. Thus, a crude oil may be used as it is removed from the ground, or it may be first processed in field units such as oil-water separators, degasers, etc. Although just how the crude oil functions in this manner in the slurry mixture is not understood, it is believed that the crude oil contains surface-active components or agents which prevent sulfur agglomeration, sticking and aids in the formation of spherical sulfur particles having dimensions of from l to 1,500 microns and preferably between 100 and 700 microns.

At the terminal end of the line the sulfur can be readily separated from the slurry by any suitable means.

PREFERRED EMBODIMENT OF THE INVENTION (1) A 4060 percent by weight sulfur-aromatic 17 percent enriched kerosene slurry was prepared by phase transfer by first injecting molten sulfur into an aqueous liquid such as water and thereafter contacting the slurry thus formed with the aromatic enriched kerosene to effect phase transfer of the sulfur particles into the aromatic enriched kerosene. To the sulfur kerosene slurry was added from about 1 percent to about 2 percent of crude oil and thereafter this slurry was injected into a pipeline for transportation to a terminal station. Sulfur-kerosene slurries containing a small amount of crude oil thus formed do not form agglomerates or did they plug the pipeline.

(ll) An advantage of the present process for transporting through pipelines sulfurliquid petroleum slurries as defined is that the slurry can be also prepared by direct injection of molten sulfur into a suitable petroleum fraction such as kerosene, fuel oil, oil condensate or distillate and mixtures thereof to which has been added a small amount of crude oil so as to aid in making spherical sulfur particles and prevent sulfur agglomeration, deposition and plugging of pipelines. Either process as well as other processes can be used to make the sulfur-liquid petroleum fraction slurry depending on the availability of the carrier. Thus, where water is available the first process can be used and if not the second one can be used.

The presence of a small amount of crude oil during the preparation of the final slurry by method (I) or (ll) has an additional advantage in that the crude oil aids in the formation of spherical sulfur particles which are most desirable since spherical sulfur particles in slurries as defined provide optimum pipeline performance such as low pressure drops during its transportation and ease of recovery and purification at the terminal end of the pipeline.

The following examples illustrate the essence of the present invention.

A. Molten sulfur at l20l60 C. was sprayed into aromatic 17 percent enriched kerosene through a spray nozzle at about 200 p.s.i. pressure drop to give a homogeneous slurry with sulfur solids content of about 16 percent by volume in which the sulfur particles were essentially large angularcrystalline particles which began to stick together and agglomerate into a sticky mass within about l 1 5 minutes.

B. The method of (A) was repeated except that 1 percent of crude oil was added to the kerosene carrier. The particles formed were microspherical (20450 microns) in shape and no tendency of the particles to stick or agglomerate was observed for over 24 hours.

In another test different petroleum fractions were used to form sulfur slurries wherein a 90-ml. portion of molten sulfur at 140 C was injected as a continuous stream for 0.5 minute into a well-stirred 500 ml. charge of a petroleum carrier. As shown in Table 1 some of the carriers were used neat and to some were added crude oil. For comparison various surfactants were added to sulfur-oil slurries and the results are shown in Table 1.

described in the copending US. Pat. application Ser. No. 684,507, filed Nov. 20, 1967 which matured as US. Pat. No. 3,489.677 which comprises treating oil contaminated sulfur with an aqueous solution containing a mixture of alkali hydrosulfide and corresponding hydroxide, e.g., ammonium hydrosulfide and ammonium hydroxide, or by other suitable means such as sulfur can be recovered from the oil slurry by filtration of molten sulfur and liquid-liquid extraction with a hydrocarbon solvent containing 10-50 percent aromatic. Thus, at the receiving terminal the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquid-liquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired, the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described method may be made within the scope of the appended claims without departing from the spirit of the invention.

We claim:

1. A method of transporting sulfur through a pipeline to a terminal without causing sulfur sticking, agglomeration and plugging of the line comprising:

a. injecting l075 percent by weight molten sulfur into from 90 percent to 25 percent ofa liquid-petroleum fraction selected from the group consisting of petroleum distillate and condensate fractions ranging in viscosity from gasoline to a heavy lube oil fraction to form a sulfurliquid petroleum slurry;

b. mixing with the slurry (a) from about 0.1 to about 10 percent of crude oil;

0. injecting the mixture (b) into a pipeline; and,

d. transporting via said pipeline the slurry (c) to a terminal station.

2. The method of claim 1 wherein the crude oil (b) is unrefined crude oil and is added to the slurry (a) after slurry (a) has been injected into a pipeline.

3. The method of claim 1 wherein the slurry (a) contains 30-70 percent by weight sulfur and the balance being a liquid petroleum condensate fraction containing from 10 percent to 30 percent aromatics and the amount of crude oil (11) added to slurry (a) is from about 0.5 percent to about 5 percent.

TABLE 1A.-EFFECT OF ADDI'IIVES ON SULFUR DISPERSION [Conditions: 500 m1. carrier in l-liter Morton flask. 90 ml. sulfur at approximately 140 C. added in 0.5 minute. 1,200 r.p.m. with crescent blade stirrer] 008E121? Major fractions,

n12 1 sierisenlt wt. mes as s s urry tInitial Level, percent emp., percent wt. basis 16 +30 -30 d Particle Carrier C. wt. Type S fed I shape l Run:

1.- Petroleum fraction (Waterton condensate) 22 None 19.1 57. 7 19.3 680 A 2 "do" 22 1 Bryton 430 (62% alkylaryl 20. 4 60.0 21.0 710 A sulfonate). 3 .do 0 24 1 Oleic acid 30 72. 0 13. 7 770 A 23 1 Naphthenlc acid bottoms 30 A 23 1 Dehydroabletic acid 30 A 6.-.. .do 21 1 50% dodecyltrimethyi- 13. 8 62. 6 20. 8 700 A ammonium chloride. 7.. 35% kerosene/white oil (Waterton condensate)... 23 0. 1 6 API crude oil 7. 0 64. 6 24. 0 690 S l S=Spheriea1: A=Agglornerated, in estimated order of abundance in +30 mesh fraction.

b 600 r.p.m. in early scouting runs and in all 0. runs.

Derived from Canadian oil field. API gravity=54.9; Viscosity, cs. 59 F.=0.953 and 77 F.=0.865' Flash m: t -80; Sulfur, percent wt. total=1.14; FIA, percent v01. Saturates=82 and Aromatics=18. p01 ag open F. Pour point, F.

Sulfur slurries of the present invention containing small amounts of crude oil additives can be transported through pipelines over great distances without the danger of sulfur deposition, agglomeration, sticking or plugging of the pipelines.

At the terminal end of the line the sulfur can be removed from the liquid hydrocarbon by suitable means such as described in US. Pat. No. 2,798,772 and the sulfur purified by methods as described in US. Pat. No. 2,809,885 or as 4. The method of claim 3 wherein the crude oil is unrefined crude oil present in the slurry between 1 percent and 2 percent.

5. The method of claim 1 wherein the sulfur-petroleum fraction slurry is separated into its component parts at the terminal end ofthe pipeline.

6. The method of claim 5 wherein the separated components of sulfur and petroleum fractions are each purified by removal of contaminants therefrom. 

2. The method of claim 1 wherein the crude oil (b) is unrefined crude oil and is added to the slurry (a) after slurry (a) has been injected into a pipeline.
 3. The method of claim 1 wherein the slurry (a) contains 30-70 percent by weight sulfur and the balance being a liquid petroleum condensate fraction containing from 10 percent to 30 percent aromatics and the amount of crude oil (b) added to slurry (a) is from about 0.5 percent to about 5 percent.
 4. The method of claim 3 wherein the crude oil is unrefined crude oil present in the slurry between 1 percent and 2 percent.
 5. The method of claim 1 wherein the sulfur-petroleum fraction slurry is separated into its component parts at the terminal end of the pipeline.
 6. The method of claim 5 wherein the separated components of sulfur and petroleum fractions are each purified by removal of contaminants therefrom. 